1. Field of the Invention
The present invention relates to a video signal recording apparatus and, more particularly, to a video signal recording apparatus for digitizing video signals and recording the digitized video signals on a recording medium.
2. Description of the Related Art
A conventional apparatus for digitally recording video signals on a recording medium is designed to conduct a process such as transformation of data arrangement (referred to as "interleave" hereinafter) before the digitized signals are recorded on a recording medium, in order to correct any error. Known interleave techniques, however, are unsatisfactory in that no specific consideration is given to prevention of deterioration of the reproduced image quality which is experienced particularly in a case where the probability of reproduction of correct data is extremely small as in the case of a special reproduction mode, e.g., when a recording medium such as a tape is transported at a speed which is different from the tape speed in the recording. More specifically, a conventional interleave process is executed in each frame, and the interleave rule is fixed and unchangeable for all frames.
When video signals recorded on a video tape is reproduced in a special reproduction mode by a conventional video signal recording apparatus, there are some portions of the tape which are omitted from the scanning coverage of the reproduction head. In addition, reproduction is often impossible even from the scanned portion of the tape, due to a difference between the azimuth of the head and the azimuth of the track. If the same interleave rule is applied to all frames, only the same line blocks are reproduced in each reproduced frame. This problem is serious particularly in the so-called high-speed searching mode. In this mode, partly because the tape running speed is an integer number times the recording tape speed and partly because the number of the reproduced data is reduced, only the specific portions in a restricted region on the picture are repeatedly reproduced, with the result that the quality of the picture is extremely degraded.
In order to obviate this problem, U.S. patent application Ser. No. 317,430 filed on Mar. 1, 1989 proposes a method in which different interleave rules are applied to different frames. This proposal makes it possible to improve the quality of reproduced image in the special reproduction mode, without causing any substantial change in hardware.